Gazpachuelo malagueño: warm emulsified fish soup

Ingredients

• For the broth
• 1 litre white fish stock, made from white fish frames
• 300 g potato, pre-cooked, sliced or diced
• For the fish
• 400 g white fish, cod, monkfish, or whitefish, cooked separately
• For the emulsion
• 150 g mayonnaise, full-flavoured, slightly sharp; good-quality commercial acceptable

Method

1. 1
   Bring the fish stock to a gentle simmer in a wide saucepan. Add the pre-cooked potato and warm through. The broth should be fully hot but not boiling — the surface should shiver, not roll.
2. 2
   Cook the fish separately — poached in a little salted water or steamed — until it just flakes when pressed. Remove from the heat and keep warm apart from the broth.
3. 3
   Remove the broth from the heat. This is where the dish lives or dies: the broth must be hot but not boiling — above 85 °C the eggs in the mayonnaise scramble. Working quickly and continuously, whisk the mayonnaise into the hot broth in a steady stream until the soup is pale, creamy, and lightly thickened. The surface should appear uniform and silky, with no threads or curds visible.
4. 4
   Taste and correct the seasoning with care — the mayonnaise contributes richness and some saltiness. The broth should be lightly sharp from the vinegar in the mayonnaise and decidedly rich without heaviness.
5. 5
   Ladle the emulsified broth with its potato into warm bowls. Lay the separately cooked fish on top as a floating element — it must not be submerged or stirred into the emulsified broth. The surface of each bowl should be pale and smooth, the fish pieces resting cleanly above it.